Outcomes after induction failure in childhood acute lymphoblastic leukemia

The journey to CAR T cell therapy: the pediatric and young adult experience with relapsed or refractory B-ALL

Outcomes of pediatric and young adult patients diagnosed with acute lymphoblastic leukemia (ALL) have improved significantly in the past few decades. Treatment advances have provided 5-year survival rates ranging from 78 to 91% depending on the age at diagnosis. However, approximately 2-3% of patients will present with refractory disease that is unresponsive to chemotherapy, and 10-15% of patients will relapse. Outcomes post-relapse show significantly reduced 5-year survival rates that continue to decrease with each subsequent relapse. Despite our increased understanding of risk factors and disease predictors, treatment strategies for patients with relapsed or refractory (r/r) disease, including variations of chemotherapy and stem cell transplant, remain ineffective for many patients. To improve outcomes of patients with r/r disease, immunotherapies targeting specific B cell antigens are being developed. Tisagenlecleucel is an autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy recently approved by the US Food and Drug Administration for patients with refractory leukemia or those with second or later relapse. In this treatment strategy, a patient's own T cells are transduced to express an anti-CD19 CAR that, when reintroduced into the patient, directs specific binding and killing of CD19+ B cells. In a phase 2, single-arm, multicenter, global study, tisagenlecleucel resulted in a remission rate of 81% in pediatric and adolescent patients with r/r B cell ALL. This review article summarizes four typical cases of pediatric and adolescent r/r B-cell ALL, focusing on the patient's journey from initial diagnosis to treatment with CAR T cell therapy.

Fluorescence in situ hybridization comparison of the prognostic factors in adult and pediatric acute lymphoblastic leukemia: A retrospective analysis of 282 cases

Acute lymphoblastic leukemia (ALL) affects both children and adults. However, the prognosis of the two cohorts is quite different. The present aim was to review and evaluate one potential cause of why survival is poorer in adult ALL than pediatric ALL via fluorescence in situ hybridization (FISH). Clinical significant features were analyzed in 282 ALL cases. FISH was performed to study mixed lineage leukemia (MLL) translocation and the Philadelphia (Ph) chromosome in newly diagnosed patients, and was used to detect trisomy 4 or 10 and the translocation ETS leukemia-acute myeloid leukemia 1 (TEL-AML1) fusion gene. The overall survival/event-free survival (OS/EFS) outcome of adult ALL and pediatric ALL was analyzed using Kaplan-Meier analysis. Adult ALL had a higher median leukocyte count and lower hemoglobin level than pediatric ALL. FISH revealed that Ph positivity (Ph+) was associated with the high-risk feature of older age. In pediatric ALL, trisomy 4 or 10 was present in 71/207 cases (34.3%), while the TEL-AML1 fusion gene was present in 16/207 cases (7.7%). By contrast, there were very few such positive cases in adult ALL. Survival analysis revealed that, in adult ALL, the 3-year OS and EFS rates were higher in the Ph-negative group than in the Ph+ group. Adult or pediatric ALL is an independent prognostic factor of OS. The present analysis of the clinical and biological features between adult and pediatric ALL indicates that adult ALL has a poorer prognosis than pediatric ALL based on Ph+ status and presence of trisomy 4 or 10. Ph+ ALL is an independent prognosis factor of ALL. FISH may serve an important role in the comparison of prognostic factors in adult and pediatric ALL.

Hedgehog pathway mutations drive oncogenic transformation in high-risk T-cell acute lymphoblastic leukemia

The role of Hedgehog signaling in normal and malignant T-cell development is controversial. Recently, Hedgehog pathway mutations have been described in T-ALL, but whether mutational activation of Hedgehog signaling drives T-cell transformation is unknown, hindering the rationale for therapeutic intervention. Here, we show that Hedgehog pathway mutations predict chemotherapy resistance in human T-ALL, and drive oncogenic transformation in a zebrafish model of the disease. We found Hedgehog pathway mutations in 16% of 109 childhood T-ALL cases, most commonly affecting its negative regulator PTCH1. Hedgehog mutations were associated with resistance to induction chemotherapy (P = 0.009). Transduction of wild-type PTCH1 into PTCH1-mutant T-ALL cells induced apoptosis (P = 0.005), a phenotype that was reversed by downstream Hedgehog pathway activation (P = 0.007). Transduction of most mutant PTCH1, SUFU, and GLI alleles into mammalian cells induced aberrant regulation of Hedgehog signaling, indicating that these mutations are pathogenic. Using a CRISPR/Cas9 system for lineage-restricted gene disruption in transgenic zebrafish, we found that ptch1 mutations accelerated the onset of notch1-induced T-ALL (P = 0.0001), and pharmacologic Hedgehog pathway inhibition had therapeutic activity. Thus, Hedgehog-activating mutations are driver oncogenic alterations in high-risk T-ALL, providing a molecular rationale for targeted therapy in this disease.

Favourable outcomes for childhood acute lymphoblastic leukaemia in an isolated setting: The Tasmanian experience

BACKGROUND

Tasmania is a large, relatively isolated island located south of mainland Australia with limited tertiary level paediatric oncology services.

AIMS

To benchmark regional outcomes for childhood acute lymphoblastic leukaemia (ALL) against published international standards.

METHODS

We undertook a retrospective cohort study, analysing the clinical characteristics and health outcomes of all children diagnosed with and treated for ALL in Tasmania, Australia between 2006 and 2015.

RESULTS

Thirty-five patients aged less than 18 years were diagnosed with ALL in the study's 10-year period. Twenty-eight cases were precursor B cell in origin, with 7 cases of T-cell ALL. The great majority of children (30/35; 86%) received their entire first line treatment in Tasmania. Major treatment-related toxicities, including allergic drug reactions, and episodes of acute pancreatitis, deep venous thrombosis and bacterial sepsis, were managed locally, with one death secondary to overwhelming infection and multiorgan failure. The overall and event-free survival rates for childhood ALL were 30/35 (86%) and 28/35 (80%), respectively.

CONCLUSIONS

These results compare favourably with published results from large international cooperative group trials based in developed countries. Continued local treatment with appropriate support from a dedicated specialist paediatric oncology unit is therefore justified.

Phase II/III study in children and adolescents with newly diagnosed B-cell precursor acute lymphoblastic leukemia: protocol for a nationwide multicenter trial in Japan

B-cell precursor acute lymphoblastic leukemia is the most common pediatric malignancy, but its treatment needs to be modified to cause low acute toxicity and few late complications with a high cure rate. In this trial, we will stratify patients with B-cell precursor acute lymphoblastic leukemia into standard, intermediate and high risk groups according to prognostic factors. In addition, we will establish an evaluation system for minimal residual disease that will enable us to stratify patients based on minimal residual disease in subsequent clinical trials. We will clarify the impact of dexamethasone/vincristine pulse therapy during maintenance therapy in the standard risk group, and intensive l-asparaginase therapy in the intermediate risk group. In the high risk group, usefulness of vincristine intensification will be assessed. This trial has been registered in the UMIN Clinical Trials Registry as UMIN000009339 [http://www.umin.ac.jp/ctr/].

The safety and efficacy of clofarabine in combination with high-dose cytarabine and total body irradiation myeloablative conditioning and allogeneic stem cell transplantation in children, adolescents, and young adults (CAYA) with poor-risk acute leukemia

Acute leukemias in children with CR3, refractory relapse, or induction failure (IF) have a poor prognosis. Clofarabine has single agent activity in relapsed leukemia and synergy with cytarabine. We sought to determine the safety and overall survival in a Phase I/II trial of conditioning with clofarabine (doses 40 - 52 mg/m²), cytarabine 1000 mg/m², and 1200 cGy TBI followed by alloSCT in children, adolescents, and young adults with poor-risk leukemia. Thirty-seven patients; Age 12 years (1-22 years); ALL/AML: 34:3 (18 IF, 10 CR3, 13 refractory relapse); 15 related, 22 unrelated donors. Probabilities of neutrophil, platelet engraftment, acute GvHD, and chronic GvHD were 94%, 84%, 49%, and 30%, respectively. Probability of day 100 TRM was 8.1%. 2-year EFS (event free survival) and OS (overall survival) were 38.6% (CI₉₅: 23-54%), and 41.3% (CI₉₅: 25-57%). Multivariate analysis demonstrated overt disease at time of transplant (relative risk (RR) 3.65, CI₉₅: 1.35-9.89, P = 0.011) and umbilical cord blood source (RR 2.17, CI₉₅: 1.33-4.15, P = 0.019) to be predictors of worse EFS/OS. This novel myeloablative conditioning regimen followed by alloSCT is safe and well tolerated in CAYA with very poor-risk ALL or AML. Further investigation in CAYA with better risk ALL and AML undergoing alloSCT is warranted.

Expression of miR-652-3p and Effect on Apoptosis and Drug Sensitivity in Pediatric Acute Lymphoblastic Leukemia

MicroRNAs (miRNAs) expression profiles were screened in plasma samples from pediatric patients with acute lymphoblastic leukemia (ALL) and healthy controls, using qRT-PCR-based TaqMan low-density miRNA arrays. MiR-652-3p (a circulating miRNA) was downregulated in new diagnosis (ND) patients compared with healthy controls. The levels of miR652-3p were restored in complete remission (CR) but were downregulated again in disease relapse (RE). The expression pattern of miR-652-3p was validated in bone marrow (BM) samples from other pediatric ALL patients. MiR-652-3p was significantly upregulated in BM when the patients (n=86) achieved CR, as compared with the matched ND samples (p<0.001). Moreover, the miR-652-3p levels in BM decreased again in two patients at RE. In addition, the lymphoblastic leukemia cell lines Reh and RS4:11 were found to have lower levels of miR-625-3p than the normal B-cell line. Overexpression of miR-652-3p using agomir increased the sensitivity to vincristine and cytarabine (all p<0.05) and promoted apoptosis (both p<0.05) in Reh and RS4:11 cells. In conclusion, the results suggested that a low level of miR-652-3p might be involved in the pathogenesis of pediatric ALL. Overexpression of miR-652-3p might suppress lymphoblastic leukemia cells, promoting apoptosis and increasing sensitivity to chemotherapeutic drugs.

BCR-ABL enhances the prolyl isomerase activity of Pin 1 by interacting with DAPK1 in ph+ ALL

Philadelphia chromosome (Ph)/BCR-ABL-positive (ph+ ) ALL is the most common genetic abnormality associated with ALL and has been shown to confer the worst prognosis to both children and adults. Increasing evidence has revealed that the dysregulation of prolyl isomerase Pin 1 contributes to multicancer development and progression, including ALL, although the underlying molecular mechanisms remain unclear. Here, we report that the expression of Pin 1 was enhanced in ph+ ALL patient samples and was associated positively with the expression of BCR-ABL. Genetically or pharmacologically inhibiting Pin 1 expression or activity produces potent therapeutic efficacy against ph+ ALL. We further demonstrated that BCR-ABL enhances the prolyl isomerase activity of Pin 1 by decreasing the phosphorylated level of Pin 1 at Ser 71 and interacting with DAPK1. The inhibition of BCR-ABL activity by imatinib in human ph+ ALL cells reduces the prolyl isomerase activity of Pin 1, further suggesting a key role of the newly identified BCR-ABL-Pin 1 axis in ph+ ALL progression. Thus, the combined suppression of Pin 1 and BCR-ABL proteins may be exploited as an additional target therapy for ph+ ALL.

Global efforts toward the cure of childhood acute lymphoblastic leukaemia

Improvements in risk-directed treatment and supportive care, together with increased reliance on both national and international collaborative studies, have made childhood acute lymphoblastic leukaemia (ALL) one of the most curable human cancers. Next-generation sequencing studies of leukaemia cells and the host germline provide new opportunities for precision medicine and thus potential improvements in the cure rate and quality of life of patients. Efforts are underway to assess the global impact of childhood ALL and develop initiatives that can meet the long-term challenge of providing quality care to children with this disease worldwide and improving cure rates globally. This ambitious task will rely on increased collaborative research and international networking so that the therapeutic gains in high-income countries can be translated to patients in low-income and middle-income countries. Ultimately, the greatest obstacle to overcome will be to fully understand leukaemogenesis, enabling measures to decrease the risk of leukaemia development and thus close the last major gap in offering a cure to any child who might have the disease.

Flow-cytometric vs. -morphologic assessment of remission in childhood acute lymphoblastic leukemia: a report from the Children's Oncology Group (COG)

Minimal residual disease (MRD) after initial therapy is integral to risk stratification in B-precursor and T-precursor acute lymphoblastic leukemia (B-ALL, T-ALL). Although MRD determines depth of remission, remission remains defined by morphology. We determined the outcomes of children with discordant assessments of remission by morphology vs. flow cytometry using patients age 1-30.99 years enrolled on Children's Oncology Group ALL trials who underwent bone marrow assessment at the end of induction (N = 9350). Morphologic response was assessed locally as M1 (<5% lymphoblasts; remission), M2 (5-25%), or M3 (>25%). MRD was centrally measured by flow cytometry. Overall, 19.8% of patients with M2/M3 morphology had MRD < 5%. M1 with MRD ≥ 5% was less common in B-ALL (0.9%) than T-ALL (6.9%; p < 0.0001). In B-ALL, M1/MRD ≥ 5% was associated with superior 5-year event-free survival (EFS) than M2/MRD ≥ 5% (59.1% ± 6.5% vs. 39.1% ± 7.9%; p = 0.009), but was inferior to M1/MRD < 5% (87.1% ± 0.4%; p < 0.0001). MRD levels were higher in M2/MRD ≥ 5% than M1/MRD ≥ 5% patients. In T-ALL, EFS was not significantly different between M1/MRD ≥ 5% and M2/MRD ≥ 5%. Patients with morphologic remission but MRD ≥ 5% have outcomes similar to those who fail to achieve morphological remission, and significantly inferior to those with M1 marrows and concordant MRD, suggesting that flow cytometry should augment the definition of remission in ALL.

CAR-T cells and allogeneic hematopoietic stem cell transplantation for relapsed/refractory B-cell acute lymphoblastic leukemia

Relapsed/refractory acute lymphoblastic leukemia (ALL) has a low remission rate after chemotherapy, a high relapse rate and poor long-term survival even when allogeneic hematopoietic stem cell transplantation (allo-HSCT) is performed. Chimeric antigen receptors redirected T cells (CAR-T cells) can enhance disease remission with a favorable outcome for relapsed/refractory ALL, though some cases quickly relapsed after CAR-T cell treatment. Thus, treatment with CAR-T cells followed by allo-HSCT may be the best way to treat relapsed/refractory ALL. In this review, we first discuss the different types of CAR-T cells. We then discuss the treatment of relapsed/refractory ALL using only CAR-T cells. Finally, we discuss the use of CAR-T cells, followed by allo-HSCT, for the treatment of relapsed/refractory ALL.

Investigating chemoresistance to improve sensitivity of childhood T-cell acute lymphoblastic leukemia to parthenolide

Current therapies for childhood T-cell acute lymphoblastic leukemia have increased survival rates to above 85% in developed countries. Unfortunately, some patients fail to respond to therapy and many suffer from serious side effects, highlighting the need to investigate other agents to treat this disease. Parthenolide, a nuclear factor kappa (κ)B inhibitor and reactive oxygen species inducer, has been shown to have excellent anti-cancer activity in pediatric leukemia xenografts, with minimal effects on normal hemopoietic cells. However, some leukemia initiating cell populations remain resistant to parthenolide. This study examined mechanisms for this resistance, including protective effects conferred by bone marrow stromal components. T-cell acute leukemia cells co-cultured with mesenchymal stem cells demonstrated significantly enhanced survival against parthenolide (73±11%) compared to cells treated without mesenchymal stem cell support (11±9%). Direct cell contact between mesenchymal cells and leukemia cells was not required to afford protection from parthenolide. Mesenchymal stem cells released thiols and protected leukemia cells from reactive oxygen species stress, which is associated with parthenolide cytotoxicity. Blocking cystine uptake by mesenchymal stem cells, using a small molecule inhibitor, prevented thiol release and significantly reduced leukemia cell resistance to parthenolide. These data indicate it may be possible to achieve greater toxicity to childhood T-cell acute lymphoblastic leukemia by combining parthenolide with inhibitors of cystine uptake.

Synergistic action of dual IGF1/R and MEK inhibition sensitizes childhood acute lymphoblastic leukemia (ALL) cells to cytotoxic agents and involves downregulation of STAT6 and PDAP1

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Dual insulin-like growth factor 1 receptor (IGF1/R) + mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibition synergistically sensitize apoptosis-resistant acute lymphoblastic leukemia (ALL) cells.

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Dual IGF1/R + MEK inhibition potentiates chemotherapy-induced killing of ALL cells.

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Signal transducer and activator of transcription 6 (STAT6) and platelet-derived growth factor-associated protein 1 (PDAP1) are downregulated differentially by this synergistic action.

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STAT6 and PDAP1 are predicted to act in a putative STAT6–ERK–nuclear factor kappa beta (NF-κB) survival network.

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Targeting this network may be useful for sensitizing ALL to chemotherapy agents.

Heterogeneous upregulation of multiple prosurvival pathways underlies resistance to damage-induced apoptosis in acute lymphoblastic leukemia (ALL) cells despite normal p53 responses. Here, we show that the dual combination of insulin-like growth factor 1 (IGF1)/IGF1 receptor (IGF1/R) and mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibition using AG1024 + U0126 can sensitize apoptosis-resistant ALL cells to ionizing radiation-induced DNA damage irrespective of effect of single pathway inhibition in vitro. This AG1024 + U0126 combination also significantly potentiates the ability of the core chemotherapy compounds vincristine, dexamethasone, and daunorubicin to kill ALL cells in vitro. Evidence of the synergistic action of AG1024 + U0126 in samples with variable basal levels of phosphorylated IGF1/Rβ and ERK1/2 suggested additional targets of this drug combination. Consistent with this, gene expression profiling identified 32 “synergy genes” differentially targeted by IGF1/R + MEK inhibition and, among these, Signal transducer and activator of transcription 6 (STAT6) and platelet-derived growth factor-associated protein 1 (PDAP1) were the most differentially downregulated cluster. Pearson correlation analysesrevealed that STAT6 and PDAP1 display significant expression codependency and a common expression pattern linked with other key “synergy” genes, supporting their predicted role in an STAT6–ERK–nuclear factor kappa beta (NF-κB) network. Knockdown studies revealed that loss of STAT6, but not PDAP1, impinges on the cell cycle, causing reduced numbers of viable cells. In combination with daunorubicin, STAT6 loss has an additive effect on cell killing, whereas PDAP1 loss is synergistic, indicating an important role of PDAP1 in the cellular response to this anthracycline. Inhibition of STAT6 or PDAP1 may therefore represent a potential novel therapeutic strategy for resistant ALL by enhancing sensitivity to chemotherapy.

Outcome of children with multiply relapsed B-cell acute lymphoblastic leukemia: a therapeutic advances in childhood leukemia & lymphoma study

The survival of pediatric patients with multiply relapsed and/or refractory (R/R) B-cell acute lymphoblastic leukemia has historically been very poor; however, data are limited in the current era. We conducted a retrospective study to determine the outcome of multiply R/R childhood B-ALL treated at 24 TACL institutions between 2005 and 2013. Patient information, treatment, and response were collected. Prognostic factors influencing the complete remission (CR) rate and event-free survival (EFS) were analyzed. The analytic set included 578 salvage treatment attempts among 325 patients. CR rates (mean ± SE) were 51 ± 4% for patients with bone marrow R/R B-ALL who underwent a second salvage attempt, 37 ± 6% for a third attempt, and 31 ± 6% for the fourth through eighth attempts combined. For patients achieving a CR after their second, third, and fourth through eighth attempts, the 2 year EFS was 41 ± 6%, 13 ± 7%, and 27 ± 13% respectively. Our results showed slight improvement when compared to previous studies. This is the largest and most recent study to date that evaluates the outcome of this patient population. Our data will provide detailed reference for the evaluation of new agents being developed for childhood B-ALL.

The assessment and appraisal of regenerative medicines and cell therapy products: an exploration of methods for review, economic evaluation and appraisal

BACKGROUND

The National Institute for Health and Care Excellence (NICE) commissioned a 'mock technology appraisal' to assess whether changes to its methods and processes are needed. This report presents the findings of independent research commissioned to inform this appraisal and the deliberations of a panel convened by NICE to evaluate the mock appraisal.

METHODS

Our research included reviews to identify issues, analysis methods and conceptual differences and the relevance of alternative decision frameworks, alongside the development of an exemplar case study of chimeric antigen receptor (CAR) T-cell therapy for treating acute lymphoblastic leukaemia.

RESULTS

An assessment of previous evaluations of regenerative medicines found that, although there were a number of evidential challenges, none was unique to regenerative medicines or was beyond the scope of existing methods used to conceptualise decision uncertainty. Regarding the clinical evidence for regenerative medicines, the issues were those associated with a limited evidence base but were not unique to regenerative medicines: small non-randomised studies, high variation in response and the intervention subject to continuing development. The relative treatment effects generated from single-arm trials are likely to be optimistic unless it is certain that the historical data have accurately estimated the efficacy of the control agent. Pivotal trials may use surrogate end points, which, on average, overestimate treatment effects. To reduce overall uncertainty, multivariate meta-analysis of all available data should be considered. Incorporating indirectly relevant but more reliable (more mature) data into the analysis can also be considered; such data may become available as a result of the evolving regulatory pathways being developed by the European Medicines Agency. For the exemplar case of CAR T-cell therapy, target product profiles (TPPs) were developed, which considered the 'curative' and 'bridging to stem-cell transplantation' treatment approaches separately. Within each TPP, three 'hypothetical' evidence sets (minimum, intermediate and mature) were generated to simulate the impact of alternative levels of precision and maturity in the clinical evidence. Subsequent assessments of cost-effectiveness were undertaken, employing the existing NICE reference case alongside additional analyses suggested within alternative frameworks. The additional exploratory analyses were undertaken to demonstrate how assessments of cost-effectiveness and uncertainty could be impacted by alternative managed entry agreements (MEAs), including price discounts, performance-related schemes and technology leasing. The panel deliberated on the range of TPPs, evidence sets and MEAs, commenting on the likely recommendations for each scenario. The panel discussed the challenges associated with the exemplar and regenerative medicines more broadly, focusing on the need for a robust quantification of the level of uncertainty in the cost-effective estimates and the potential value of MEAs in limiting the exposure of the NHS to high upfront costs and loss associated with a wrong decision.

CONCLUSIONS

It is to be expected that there will be a significant level of uncertainty in determining the clinical effectiveness of regenerative medicines and their long-term costs and benefits, but the existing methods available to estimate the implications of this uncertainty are sufficient. The use of risk sharing and MEAs between the NHS and manufacturers of regenerative medicines should be investigated further.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Early bacterial and fungal infection in children receiving allogeneic stem cell transplantation for acute lymphoblastic leukemia in Argentina

Infections are important complications associated with allogeneic HSCT. Describing infection rates in low- and middle-income countries provides data to infer efficacy of supportive care practices in these settings. In this retrospective cohort study, we included patients (age ≤ 18 years) who underwent a first allogeneic HSCT for ALL in a single center in Argentina between 1998 and 2016. The primary outcome was sterile site bacterial infection. Secondary outcomes were proven or probable invasive fungal infection, TRM, and infectious deaths. There were 68 allogeneic HSCT recipients with ALL included in this analysis. Overall, 17 (25.0%) experienced at least one sterile site bacterial infection and 10 (14.7%) experienced at least one proven or probable invasive fungal infection. The TRM rate was 19.1%, and 3 (4.4%) patients died of infection. In a middle-income country center in Argentina, pediatric allogeneic HSCT infection rates, TRM, and infection-related mortality were comparable to high-income countries. These data support continuation of allogeneic HSCT programs in similar resource-limited settings provided that adequate supportive care and monitoring of outcomes can be performed.

Haploidentical hematopoietic SCT using helical tomotherapy for total-body irradiation and targeted dose boost in patients with high-risk/refractory acute lymphoblastic leukemia

A novel conditioning regimen using helical tomotherapy (HT) was developed to deliver 10 Gy for total body irradiation (TBI) and simultaneously augment dose to 12 Gy for targeted dose boost to total marrow, central nervous system leukemia, and extramedullary disease sites in patients with high-risk or relapsed/refractory acute lymphoblastic leukemia (ALL) receiving haploidentical allogeneic hematopoietic stem cell transplantation (allo-HSCT). Fourteen patients were included, eight of these patients were in first complete remission (CR1), one was in CR2, one had a partial response and four patients had refractory disease at transplantation. The median delivered average dose was 11.395 Gy (range 10.06-12.17). The median planning target volume D95 was 8.2 Gy (range 7.52-9.01). The median delivered dose to skeleton bone with active bone marrow sites was 12.685 Gy (range 11.12-13.52). The results of this trial suggest that using HT TBI confers satisfactory immunosuppression and excellent eradication of malignant cells in patients with high-risk ALL undergoing allo-HSCT, especially in those with refractory ALL. After a median follow-up of 14.6 months (range 4-28), four patients experienced non-relapse mortality, ten patients are alive in durable CR including remission of extramedullary leukemic infiltration. One-year overall survival and disease-free survival rates post-transplantation were both 70.7%.

Characteristics and Therapeutic Targeting of Minimal Residual Disease in Childhood Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Early response to therapy, especially the measurement of minimal residual disease (MRD), remains the most reliable and strongest independent prognostic parameter. Intriguingly, little is known on the mechanisms sustaining MRD in that disease. Here, we summarize existing evidence on the influences of molecular genetics and clonal architecture of childhood ALL on disease persistence. Also, the impact of the leukemic niche on residual leukemia cells in the bone marrow and extramedullary compartments is reviewed. We further discuss existing in vivo models of minimal residual disease based on different cellular labelling strategies and engraftment of ALL cells in immunodeficient mouse strains. We finally draw some conclusions on potential strategies targeting residual ALL cells, with a focus on cellular and antibody-based immunotherapy.

Oncogenetic mutations combined with MRD improve outcome prediction in pediatric T-cell acute lymphoblastic leukemia

Risk stratification in childhood T-cell acute lymphoblastic leukemia (T-ALL) is mainly based on minimal residual disease (MRD) quantification. Whether oncogenetic mutation profiles can improve the discrimination of MRD-defined risk categories was unknown. Two hundred and twenty FRALLE2000T-treated patients were tested retrospectively for NOTCH1/FBXW7/RAS and PTEN alterations. Patients with NOTCH1/FBXW7 (N/F) mutations and RAS/PTEN (R/P) germ line (GL) were classified as oncogenetic low risk (gLoR; n = 111), whereas those with N/F GL and R/P GL mutations or N/F and R/P mutations were classified as high risk (gHiR; n = 109). Day 35 MRD status was available for 191 patients. Five-year cumulative incidence of relapse (CIR) and disease-free survival were 36% and 60% for gHiR patients and 11% and 89% for gLoR patients, respectively. Importantly, among the 60% of patients with MRD <10^-4, 5-year CIR was 29% for gHiR patients and 4% for gLoR patients. Based on multivariable Cox models and stepwise selection, the 3 most discriminating variables were the oncogenetic classifier, MRD, and white blood cell (WBC) count. Patients harboring a WBC count ≥200 × 10⁹/L, gHiR classifier, and MRD ≥10^-4 demonstrated a 5-year CIR of 46%, whereas the 58 patients (30%) with a WBC count <200 × 10⁹/L, gLoR classifier, and MRD <10^-4 had a very low risk of relapse, with a 5-year CIR of only 2%. In childhood T-ALL, the N/F/R/P mutation profile is an independent predictor of relapse. When combined with MRD and a WBC count ≥200 × 10⁹/L, it identifies a significant subgroup of patients with a low risk of relapse.

When Less Is Good, Is None Better? The Prognostic and Therapeutic Significance of Peri-Transplant Minimal Residual Disease Assessment in Pediatric Acute Lymphoblastic Leukemia

The measurement of minimal residual disease (MRD) in pediatric acute lymphoblastic leukemia (ALL) has become the most important prognostic tool of, and the backbone to, upfront risk stratification. While MRD assessment is the standard of care for assessing response and predicting outcomes for pediatric patients with ALL receiving chemotherapy, its use in allogeneic hematopoietic stem cell transplant (HSCT) has been less clearly defined. Herein, we discuss the importance of MRD assessment during the peri-HSCT period and its role in prognostication and management.

High hyperdiploid acute lymphoblastic leukemia (ALL)-A 25-year population-based survey of the Austrian ALL-BFM (Berlin-Frankfurt-Münster) Study Group

BACKGROUND

Approximately 30% of childhood acute lymphoblastic leukemia (ALL) cases are high hyperdiploid (HD). Despite their low relative recurrence risk, this group accounts for the overall largest relapse proportion.

PROCEDURE

To evaluate potential risk factors in our population-based cohort of patients with HD ALL enrolled in four Austrian ALL-BFM (Berlin-Frankfurt-Münster) studies from 1986 to 2010 (n = 210), we reviewed the clinical, laboratory, and cytogenetic data of the respective cases in relation to their outcome.

RESULTS

The 5-year event-free (EFS) and overall survival (OS) of the entire group was 83.1 ± 2.7% and 92.0 ± 1.9%, respectively. Univariate analysis revealed that trisomy 17 was significantly associated with a better EFS and OS, whereas trisomy 10 and a modal chromosome number (MCN) > 53 chromosomes were significantly associated with a better OS. Except for the latter, findings remained valid in multivariate analysis.

CONCLUSIONS

In line with previous studies, our retrospective analysis shows that MCN and specific trisomies are relevant prognostic indicators in an ALL-BFM cohort of patients with HD ALL. However, considering the current dominant role of minimal residual disease monitoring for prognostic stratification in ALL, including this particular subgroup, it is unlikely that this information is compelling enough to be utilized for refined risk classification in future ALL-BFM treatment protocols.

Prognostic factors and treatment of pediatric acute lymphoblastic leukemia

The event-free survival (EFS) for pediatric acute lymphoblastic leukemia (ALL) has shown remarkable improvement in the past several decades. In Korea also, a recent study showed 10-year EFS of 78.5%. Much of the improved outcome for pediatric ALL stems from the accurate identification of prognostic factors, the designation of risk group based on these factors, and treatment of appropriate duration and intensity according to risk group, done within the setting of cooperative clinical trials. The schema of first-line therapy for ALL remains mostly unchanged, although many groups have now reported on the elimination of cranial irradiation in all patients with low rates of central nervous system relapse. Specific high risk subgroups, such as Philadelphia chromosome-positive (Ph+) ALL and infant ALL continue to have significantly lower survival than other ALL patients. The introduction of tyrosine kinase inhibitors into therapy has led to enhanced outcome for Ph+ ALL patients. Infant ALL patients, particularly those with MLL rearrangements, continue to have poor outcome, despite treatment intensification including allogeneic hematopoietic cell transplantation. Relapsed ALL is a leading cause of mortality in pediatric cancer. Recent advances in immunotherapy targeting the CD19 of the ALL blast have shown remarkable efficacy in some of these relapsed and refractory patients. With improved survival, much of the current focus is on decreasing the long-term toxicities of treatment.

Pediatric haematopoiesis and related malignancies

Survival after acute paediatric (0–14 years), adolescent (15–19 years) and young adult (20–39 years) leukaemia has improved substantially over the last five decades, particularly for acute lymphoblastic leukaemia (ALL) and acute promyelocytic leukaemia. This progress represents one of the most successful achievements in the history of medicine and has been attributed to the development of effective chemotherapy regimens, improvement in supportive care, better risk stratification, use of targeted therapies, and advances in haematopoietic stem cell transplantation. Recent studies have revealed improvement in survival over time for all age groups and subtypes of leukaemia. However, these outcomes varied widely by age and are associated with sociodemographic and clinical factors. The present review concludes that survival and early death after acute leukaemia has greatly improved among young patients. However, inequalities in outcomes remain and are likely a result of multiple factors.

Anti-leukaemic activity of the TYK2 selective inhibitor NDI-031301 in T-cell acute lymphoblastic leukaemia

Activation of tyrosine kinase 2 (TYK2) contributes to the aberrant survival of T-cell acute lymphoblastic leukaemia (T-ALL) cells. Here we demonstrate the anti-leukaemic activity of a novel TYK2 inhibitor, NDI-031301. NDI-031301 is a potent and selective inhibitor of TYK2 that induced robust growth inhibition of human T-ALL cell lines. NDI-031301 treatment of human T-ALL cell lines resulted in induction of apoptosis that was not observed with the JAK inhibitors tofacitinib and baricitinib. Further investigation revealed that NDI-031301 treatment uniquely leads to activation of three mitogen-activated protein kinases (MAPKs), resulting in phosphorylation of ERK, SAPK/JNK and p38 MAPK coincident with PARP cleavage. Activation of p38 MAPK occurred within 1 h of NDI-031301 treatment and was responsible for NDI-031301-induced T-ALL cell death, as pharmacological inhibition of p38 MAPK partially rescued apoptosis induced by TYK2 inhibitor. Finally, daily oral administration of NDI-031301 at 100 mg/kg bid to immunodeficient mice engrafted with KOPT-K1 T-ALL cells was well tolerated, and led to decreased tumour burden and a significant survival benefit. These results support selective inhibition of TYK2 as a promising potential therapeutic strategy for T-ALL.

Influence of Musculoskeletal Manifestations as the Only Presenting Symptom in B-Cell Acute Lymphoblastic Leukemia

OBJECTIVE

To evaluate the clinical and prognostic impact of musculoskeletal manifestations as the only initial presenting symptom in childhood acute lymphoblastic leukemia (ALL).

STUDY DESIGN

We retrospectively reviewed 158 children with precursor B-cell type ALL who were followed up for >2 years. The patients were assigned to the groups musculoskeletal manifestations (n = 24) or nonmusculoskeletal manifestations (n = 134) based on initial presenting symptom. The symptom duration (regarding any initial presenting symptom) and the leukemic symptom duration (regarding symptoms of systemic manifestation, such as fever, bleeding, or pallor) were assessed, along with other clinical characteristics.

RESULTS

The musculoskeletal manifestations group exhibited a longer symptom duration than the nonmusculoskeletal manifestations group (43 days vs 22 days, P = .006), but overall survival did not significantly differ between the groups. Multivariate analysis indicated that a longer symptom duration did not affect prognosis but that a longer leukemic symptom duration was associated with a poorer prognosis (hazard ratio, 7.720; P = .048).

CONCLUSION

Musculoskeletal manifestations are associated significantly with diagnostic delay, but this delay does not affect the prognosis. Diagnostic delay after the onset of leukemic symptoms, however, does appear to affect the prognosis. Intensive evaluations for hematologic malignancies may be unnecessary in children who complain of limb pain without any definite cause, unless they also present with accompanying leukemic symptoms.

Use of Minimal Residual Disease Assessment to Redefine Induction Failure in Pediatric Acute Lymphoblastic Leukemia

Purpose

Our aim was to determine the role of end-of-induction (EOI) minimal residual disease (MRD) assessment in the identification and stratification of induction failure in patients with pediatric acute lymphoblastic leukemia (ALL) and to identify genetic abnormalities that drive disease in these patients.

Patients and Methods

Analysis included 3,113 patients who were treated in the Medical Research Council UKALL2003 multicenter randomized trial (NCT00222612) between 2003 and 2011. MRD was measured by using standardized real-time quantitative PCR. Median follow-up was 5 years 9 months.

Results

Fifty-nine patients (1.9%) had morphologic induction failure with 5-year event-free survival (EFS) of 50.7% (95% CI, 37.4 to 64.0) and 5-year overall survival of 57.7% (95% CI, 44.2 to 71.2). Of these, a small proportion of patients with M2 marrow (6 of 44) and a low EOI MRD level (< 0.01%) had 5-year EFS of 100%. Conversely, among patients with morphologic remission 2.3% (61 of 2,633) had high MRD (≥ 5%) and 5-year EFS of 47.0% (95% CI, 32.9 to 61.1), which was similar to those with morphologic induction failure. Redefining induction failure to include morphologic induction failure and/or MRD ≥ 5% identified 3.9% (120 of 3,133 patients) of the trial cohort with 5-year EFS of 48.0% (95% CI, 39.3 to 58.6). Induction failure (morphologic or MRD ≥ 5%) occurred most frequently in T-ALL (10.1%; 39 of 386 T-ALL cases) and B-other ALL, that is, lacking established chromosomal abnormalities (5.6%; 43 of 772 B-other cases). Genetic testing within the B-other group revealed the presence of PDGFRB gene fusions, particularly EBF1-PDGFRB, in almost one third of B-other ALL cases.

Conclusion

Integration of EOI MRD level with morphology identifies induction failure more precisely than morphology alone. Prevalence of EBF1-PDGFRB fusions in this group highlights the importance of genetic screening to identify abnormalities that may be targets for novel agents.

Ex vivo drug response profiling detects recurrent sensitivity patterns in drug-resistant acute lymphoblastic leukemia

Drug sensitivity and resistance testing on diagnostic leukemia samples should provide important functional information to guide actionable target and biomarker discovery. We provide proof of concept data by profiling 60 drugs on 68 acute lymphoblastic leukemia (ALL) samples mostly from resistant disease in cocultures of bone marrow stromal cells. Patient-derived xenografts retained the original pattern of mutations found in the matched patient material. Stromal coculture did not prevent leukemia cell cycle activity, but a specific sensitivity profile to cell cycle-related drugs identified samples with higher cell proliferation both in vitro and in vivo as leukemia xenografts. In patients with refractory relapses, individual patterns of marked drug resistance and exceptional responses to new agents of immediate clinical relevance were detected. The BCL2-inhibitor venetoclax was highly active below 10 nM in B-cell precursor ALL (BCP-ALL) subsets, including MLL-AF4 and TCF3-HLF ALL, and in some T-cell ALLs (T-ALLs), predicting in vivo activity as a single agent and in combination with dexamethasone and vincristine. Unexpected sensitivity to dasatinib with half maximal inhibitory concentration values below 20 nM was detected in 2 independent T-ALL cohorts, which correlated with similar cytotoxic activity of the SRC inhibitor KX2-391 and inhibition of SRC phosphorylation. A patient with refractory T-ALL was treated with dasatinib on the basis of drug profiling information and achieved a 5-month remission. Thus, drug profiling captures disease-relevant features and unexpected sensitivity to relevant drugs, which warrants further exploration of this functional assay in the context of clinical trials to develop drug repurposing strategies for patients with urgent medical needs.

The promise of chimeric antigen receptor T cells (CARTs) in leukaemia

The success of genetically engineered T cells that express chimeric antigen receptors (CARTs) has been a momentous step forward in harnessing the potent cancer fighting abilities of the immune system. The efficacy seen in relapsed/refractory (r/r) acute lymphoblastic leukaemia (ALL), not only by inducing remission, but also in maintaining long-term disease control, has been unprecedented. While the foundation for this approach has been firmly set in place, continued development will improve the efficacy, toxicity and applicability to other malignancies of this new class of 'living drugs'. In this review, we provide a comprehensive overview of the most current clinical trial data in both acute and chronic leukaemias, and discuss some of the potential ways to enhance the activity and safety of CART therapy going forward.

Recent advances in the management of pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common malignancy in childhood. Despite enormous improvement of prognosis during the last half century, ALL remains a major cause of childhood cancer-related mortality. During the past decade, whole genomic methods have enhanced our knowledge of disease biology. Stratification of therapy according to early treatment response measured by minimal residual disease allows risk group assignment into different treatment arms, ranging from reduction to intensification of treatment. Progress has been achieved in academic clinical trials by optimization of combined chemotherapy, which continues to be the mainstay of contemporary treatment. The availability of suitable volunteer main histocompatibility antigen-matched unrelated donors has increased the rates of hematopoietic stem cell transplantation (HSCT) over the past two decades. Allogeneic HSCT has become an alternative treatment for selected, very-high-risk patients. However, intensive treatment burdens children with severe acute toxic effects that can cause permanent organ damage and even toxic death. Immunotherapeutic approaches have recently come to the forefront in ALL therapy. Monoclonal antibodies blinatumomab and inotuzumab ozogamicin as well as gene-modified T cells directed to specific target antigens have shown efficacy against resistant/relapsed leukemia in phase I/II studies. Integration of these newer modalities into combined regimens with chemotherapy may rescue a subset of children not curable by contemporary therapy. Another major challenge will be to incorporate less toxic regimens into the therapy of patients with low-risk disease who have a nearly 100% chance of being cured, and the ultimate goal is to improve their quality of life while maintaining a high cure rate.

Investigating CD99 Expression in Leukemia Propagating Cells in Childhood T Cell Acute Lymphoblastic Leukemia

A significant number of children with T-lineage acute lymphoblastic leukemia (T-ALL) fail to respond to therapy and experience early relapse. CD99 has been shown to be overexpressed on T-ALL cells and is considered to be a reliable detector of the disease. However, the relevance of CD99 overexpression in ALL has not been investigated in a functional context. The aim of this study was to investigate the functional capacity of CD99⁺ cells in childhood ALL and determine the suitability of CD99 as a therapeutic target. Flow cytometric analyses confirmed higher expression of CD99 in ALL blasts (81.5±22.7%) compared to normal hemopoietic stem cells (27.5±21.9%) and T cells (3.1±5.2%, P≤0.004). When ALL cells were sorted and assessed in functional assays, all 4 subpopulations (CD34⁺/CD99⁺, CD34⁺/CD99^-, CD34^-/CD99⁺ and CD34^-/CD99^-) could proliferate in vitro and establish leukemia in NSG mice. Leukemia propagating cell frequencies ranged from 1 in 300 to 1 in 7.4x10⁴ but were highest in the CD34⁺/CD99^- subpopulation. In addition, all four subpopulations had self-renewal ability in secondary NSG mice. Cells in each subpopulation contained patient specific TCR rearrangements and karyotypic changes that were preserved with passage through serial NSG transplants. Despite high levels of CD99 antigen on the majority of blast cells, leukemia initiating capacity in vivo was not restricted to cells that express this protein. Consequently, targeting CD99 alone would not eliminate all T-ALL cells with the ability to maintain the disease. The challenge remains to develop therapeutic strategies that can eliminate all leukemia cells with self-renewal capacity in vivo.

Improvement of the Outcome of Relapsed or Refractory Acute Lymphoblastic Leukemia in Children Using a Risk-Based Treatment Strategy

Relapsed/refractory acute lymphoblastic leukemia (ALL) is a leading cause of death by cancer in children. Our institution has switched relapse treatment strategy to improve survival. We reviewed records of first relapse/refractory childhood ALL between 1996 and 2012. Based on length of first remission, relapse site and immunophenotype, patients were classified into two groups: standard-risk relapse (SRR) and high-risk relapse and refractory (HRRR). Before 2007, all patients were uniformly treated with the same induction as at presentation, followed by hematopoietic stem cell transplantation (HSCT). Since 2007, treatment was given according to risk of failure: SRR were mostly treated with chemotherapy; HRRR patients underwent HSCT after intensive chemotherapy, aiming reduction of pre-transplant disease burden. Sixty-four patients were included. Thirty (47%) were SRR and 34 (53%) HRRR, including 11 with refractory ALL. Five-years overall survival (OS) and event-free survival (EFS) were similar for SRR, but were significantly higher with new risk-based strategy for HRRR: 56% versus 17% (P = 0.03) for OS, and 56% vs 11% for EFS (P = 0.008), respectively. In multivariate analysis, treatment strategy was significantly associated with survival. In conclusion, change for a risk-based strategy in our institution increased survival of high-risk patients to levels similar of those of standard-risk patients.

Clinical impact of minimal residual disease in children with different subtypes of acute lymphoblastic leukemia treated with Response-Adapted therapy

To determine the clinical significance of minimal residual disease (MRD) in patients with prognostically relevant subtypes of childhood acute lymphoblastic leukemia (ALL), we analyzed data from 488 patients treated in St Jude Total Therapy Study XV with treatment intensity based mainly on MRD levels measured during remission induction. MRD levels on day 19 predicted treatment outcome for patients with hyperdiploid >50 ALL, National Cancer Institute (NCI) standard-risk B-ALL or T-cell ALL, while MRD levels on day 46 were prognostic for patients with NCI standard-risk or high-risk B-ALL. Patients with t(12;21)/(ETV6-RUNX1) or hyperdiploidy >50 ALL had the best prognosis; those with a negative MRD on day 19 had a particularly low risk of relapse: 1.9% and 3.8%, respectively. Patients with NCI high-risk B-ALL or T-cell ALL had an inferior outcome; even with undetectable MRD on day 46, cumulative risk of relapse was 12.7% and 15.5%, respectively. Among patients with NCI standard-risk B-ALL, the outcome was intermediate overall but was poor if MRD was ⩾1% on day 19 or MRD was detectable at any level on day 46. Our results indicate that the clinical impact of MRD on treatment outcome in childhood ALL varies considerably according to leukemia subtype and time of measurement.

Role of peripheral blood minimum residual disease at day 8 of induction therapy in high-risk pediatric patients with acute lymphocytic leukemia

Risk stratification and treatment intensification, based on minimal residual disease (MRD) mensurement, changed the prognosis of pediatric patients with acute lymphocytic leukemia (ALL). The main aim of this study was to investigate whether peripheral blood (PB) MRD measurement at day 8 (D8) could predict the risk stratification category determined by bone marrow (BM) MRD at day 15 (D15). The study was performed prospectively, in a cohort of 40 children with B-lineage ALL, adopting the protocol of the Brazilian Cooperative Group of the Treatment Childhood Leukemia (GBTLI-2009). MRD was detected by flow cytometry (FC) using a simplifed panel that can reliably identify MRD at early phases of induction therapy. Upon diagnosis, the proportion of low and high-risk patients, was 24:16 (60%:40%). The main result of our study demonstrated the potential of D8 MRD in anticipating of week the risk stratification of high-risk patients as determined by D15 BM MRD. In these patients D8 MRD level of 1% was able to segregate high risk fast responders from high risk slow responders (p = 0.0097). This result could represent an opportunity for early treatment intensification, as already performed in some protocols.

Minimal Residual Disease and Childhood Leukemia: Standard of Care Recommendations From the Pediatric Oncology Group of Ontario MRD Working Group

Minimal residual disease (MRD) is an independent predictor of relapse risk in children with leukemia and is widely used for risk-adapted treatment. This article summarizes current evidence supporting the use of MRD, including clinical significance, current international clinical practice, impact statement, and recommended indications. The proposed MRD recommendations have been endorsed by the MRD Working Group of the Pediatric Oncology Group of Ontario and provide the foundation for a strategy that aims at equitable access to MRD evaluation for children with leukemia.

Control of leukemia relapse after allogeneic hematopoietic stem cell transplantation: integrating transplantation with genetically modified T cell therapies

PURPOSE OF REVIEW

Leukemia relapse remains a significant cause of failure after allogeneic hematopoietic stem cell transplantation (HSCT). Although it is widely accepted that immunological components of the stem cell graft play a critical role in promoting leukemia eradication (graft versus leukemia effect), it is also evident that their efficacy is frequently inadequate and leukemia relapse still occurs. This article reviews recent insights into T cell-based posttransplant immunotherapy approaches aimed at preventing or controlling leukemia relapse.

RECENT FINDINGS

Donor lymphocyte infusion with T cells genetically modified with safety switches improves the patient's immune reconstitution while offering appropriate control of graft versus host disease. T lymphocytes engineered with artificial tumor-specific receptors such as αβT-cell receptor chains or chimeric antigen receptors are major players in promoting antileukemia effects after allogeneic HSCT.

SUMMARY

The landscape of adoptive T cell therapies after allogeneic HSCT has seen significant achievements with the introduction of T cell engineering. Gene transfer grants the generation of T cell products characterized by standardizable specificity and functionality. This aspect is critical for scalable and reproducible approaches for application in large clinical studies. The clinical results so far reported are encouraging and multicenter studies conducted by pharmaceutical companies will provide definitive conclusions on the clinical impact of these new methodologies.

Dexamethasone vs prednisone in induction treatment of pediatric ALL: results of the randomized trial AIEOP-BFM ALL 2000

Dexamethasone vs prednisone in induction of pediatric ALL led to significant relapse reduction and increased treatment-related mortality. No overall survival benefit was achieved with dexamethasone except in the subset of patients with T-cell ALL and good early treatment response.

Analysis of outcomes and prognostic factors of acute lymphoblastic leukemia patients treated by MCP841 protocol: A regional cancer center experience

Background:

A dramatic improvement in the survival of acute lymphoblastic leukemia (ALL) patients in the last three decades has been observed. MCP 841 protocol is an old but effective tool with tolerable toxicities. The objective of this study was to estimate the relapse-free survival of ALL patients treated uniformly with MCP 841 protocol on the basis of various prognostic factors.

Materials and Methods:

The study design was retrospective and it was conducted in a regional cancer center of Northwest India. Three hundred and ten ALL patients who underwent treatment with MCP 841 protocol and regular follow-up for up to 5 years were selected for this study. Relapse-free survival was calculated by Kaplan–Meier analysis and Cox regression analysis was used to calculate the hazards ratio (HR) using Statistical Package for the Social Sciences (SPSS) software for windows version 20.0.

Results:

Fifty-four percent patients were <15 years of age and 69% were males. 53.2% patients were in remission at the end of 5 years of starting the treatment. Relapse-free survival at 5 years by Kaplan–Meir analysis for B-cell ALL was 62% [HR 0.67 {95% confidence interval (CI) 0.47-0.95}] with patients with unknown lineage taken as reference] while for T cell it was 28% [HR 1.41 (95% CI 1.19-1.63), P 0.001]. Patients with total leukocyte count (TLC) <1 lakh/cmm at presentation, relapse-free survival was 68% and those with TLC >1 lakh/cmm had 41% survival [HR 2.14 (1.76-2.48) with, P < 0.001].

Conclusion:

MCP 841 protocol is a useful tool for the treatment of ALL in children when more aggressive protocols can not be used.